Because aggressive children are at significant risk for adjustment difficulties, childhood aggression has been a major focus of concern for researchers and other professionals during the past several decades. Although many important advances have been made, past studies have been limited in two important ways: (1) aggressive boys have received most of the research attention, whereas aggressive girls have often been excluded from relevant studies; and (2) forms of aggression that are salient to boys have been emphasized whereas forms that are salient to girls have largely been ignored. The present research is designed to address these issues through the study of aggressive children of both sexes and through the assessment of aggressive behaviors that have been shown to be prevalent among girls (relational aggression), as well as those that have been shown to be prevalent among boys (overt aggression). In contrast to overt aggression, which inflicts harm through physical damage or the threat of such damage, relational aggression harms others through damage to their peer relationships. Recent research by the PI has shown that study of this form of aggression may be crucial to understanding the aggressive development of girls. The objectives of this longitudinal investigation are: (a) to compare the concurrent and future social- psychological risk status associated with overt and relational aggression for both sexes; (b) to test the hypothesis that the social-information- processing (SIP) patterns that have been shown to play a significant role in the development and maintenance of overtly aggressive behavior problems for boys also contribute to aggressive tendencies for overtly aggressive girls and relationally aggressive girls and boys (based on a SIP model proposed by Crick and Dodge, 1994); and (c) to assess the long- term stability of overt and relational forms of aggression for both boys and girls. Two samples of children will be recruited during third grade and followed for four years: (1) a representative sample (n=120); and (2) an extreme-groups sample (n=280) of overtly aggressive; relationally aggressive; overtly plus relationally aggressive; and nonaggressive children (35 boys and 35 girls per group). This study has the potential to contribute important information about the antecedents and consequences of aggression for girls, as well as for boys, knowledge that can be used to develop empirically-based interventions for aggressive children of both sexes.